Frangible slip and expander cone segments



M. P. LEBOURG Filed Oct. 7, 1968 Maur/ce x. Zebou/y INVENTOR. BY w Lfi/g United States Patent O 3,506,067 FRANGIBLE SLIP AND EXPANDER CONE SEGMENTS Maurice P. Lehourg, Houston, Tex., assignor t Schlumberger Technology Corporation, New York, N.Y., a corporation of Texas Filed Oct. 7, 1968, Ser. No. 765,382 Int. Cl. E21b 23/06, 33/129 U.S. Cl. 166134 8 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to well tools and more particularly to anchoring systems for use on a well tool. Packers or plugs which are generally permanently set in a well bore typically use slip type anchoring means. The slips are generally provided with wickers or teeth on their external surface which, when the slips are expanded, bite or dig into the casing or tubing wall to couple or anchor the well tool in a well bore. If it is later desired to remove the tool, this can be accomplished by drilling, milling or chipping. In these cases, it is desirabe to fabricate the slips as well as the well tool from a material such as cast iron or magnesium alloys so that it may easily be broken by the action of a bit.

The slip assembly normally must be maintained in a retracted position during passage through a well =bore until such time as it is desired to anchor the tool by setting the slips. At this time the tool is actuated and the slips are forced radially outward to engage the surrounding casing and provide an anchor for the tool.

An approach taken by the prior art has been to use one piece annular slip constructions of a frangible material such as cast iron. To set the slips, a separate conical or frusto-conical expander is forced inside the slip member to break the frangible material along longitudinal lines and form fragmented slip segments. To enhance and control the breaking action, such prior art devices may have longitudinally extending weakened sections. Another approach taken by the prior art is to construct relatively large separate slip segments of a frangible material. When it is desired to activate the tool, the slip segments are expanded radially outward by a separate expander cone into engagement with the casing. During expansion the slip segments typically are held together by some retaining means such as a spring. Upon engagement with the casing, further intrusion of the expander cone fractures the large slip segments into smaller longitudinal sections more nearly matching the curvature of the casing and anchors the tool to the casing.

Generally the expander means used to expand the slips into contact with the casing is an annular, frusto-conical shaped, solid ring which is positioned about a central mandrel running the length of the tool body. And upward or downward longitudinal movement of the mandrel relative to the slips then causes the expander cone to be forced inside the surrounding annular slip assembly thus, gradu- 3,506,067 Patented Apr. 14, 1970 ally expanding it radially outwardly into engagement with the well casing. Prior art expander cones have typically been machined from steel or iron. The machining of such a piece of material generally requires a substantial amount of labor and increases the cost of the well tool accordingly. Additionally, prior art slips themselves may require some machining of their surfaces Which further increases the amount of labor and the cost of the tool.

It is an object of this invention to provide a versatile, economical slip and expander combination which can readily be formed of cast material and requiring little or no machine work.

It is a further object of this invention to provide a combination expander cone and slip type anchoring means for a well tool which may be used on any of a plurality of such tools designed to accept such an anchoring system.

Another object of this invention is to provide a well tool anchoring system comprising a plurality of arcuately shaped, combination expander cone and slip elements initially formed in a one piece casting and adapted to be placed around the central mandrel of a well tool in a staggered overlapping manner.

BRIEF DESCRIPTION OF THE INVENTION In the well tool of the present invention, the anchoring system includes a plurality of frangible slip and expander cone segments, each of an arcuate shape and adapted to be positioned surrounding the central mandrel of the tool in an overlapping manner. These slips and expander cone segments are one-piece castings of a frangible material designed to fracture along predetermined weakened connecting links or bridges when it is desired to anchor the well tool in the well bore. Each slip and expander segment is comprised of two portions; an inner expander cone portion, and stagger spaced relative to this, an outer slip segment portion. The slip segment portion is provided on its exterior surface with teeth or wickers for grippingly engaging the inner wall of a well casing. The inner surface of the slip portion is of a frusto-conical shape to cooperatively engage the outer surface of the adjacent stagger spaced expander cone portion of the casting.

As cast, the expander cone portion and the slip portion are joined along their adjacent edges by narrow bridges or webs. When oppositely directed longitudinal forces are applied to the two portions of the casting, these narrow bridges are fractured, thus allowing relative movement between the two parts of the previously unitary casting. As the longitudinal forces are applied still further, the underlying expander cone portion of the adjacent casting forces the slip portion radially outward into engagement with the inner wall of the well easing thus anchoring the tool in position.

The novel features of the present invention are set forth with particularity in the appended claims. The pres ent invention both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by way of illustration and an example of an embodiment when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic, partially sectioned view showing the well tool of the present invention in the environment of a well bore.

FIG. 2 is a top view of a plurality of the combination slip and expander cone segments of the present invention.

FIG. 3 is a perspective view of one slip and expander cone segment of the present invention before it is fractured, and

FIG. 4 is a side view of the slip and expander cone segment of the present invention along line 4-4 of FIG. 2 and after fracturing and during the setting operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention concerns an improved, unitary, breakable slip and expander anchoring system for use on oil well tools. A very economical well tool anchoring means is provided by a plurality of the combination slip and expander cone segments in one-piece casting which are positioned in a staggered, overlapping manner about the central mandrel of the well tool.

In FIG. 1, a well casing 11 is shown traversing earth formations and cemented in place. A well tool 12, such as a permanent bridge plug, is suspended in casing 11 by means of a wireline 13. The bridge plug has a central mandrel 15 which carries from top to bottom an upper slip assembly 16, a packing element 18 and a lower slip assembly 20. The setting tool 17 is a conventional gas operated type and is utilized to set the slips and expand the packing element 18 when it is desired to anchor the bridge plug in position. A setting head 30 containing a conventional lock ring 29 can be positioned above the upper slip assembly 16 to lock the well tool 12 in set condition.

The arrangement is such that when mandrel 15 is moved upwardly relative to the setting head 30 upper slip assembly 16 is operated due to forces supplied by setting tool 17 until the slips grip the casing. Then the packing element is compressed and expanded, and finally the lower slips 20 are expanded radially outwardly against the casing 11.

Components of upper slip assembly 16 are shown in more detail in FIGS. 2, 3 and 4. As may readily be seen, upper slip assembly 16 is comprised of a plurality of arcuately shaped, stagger spaced, combination slip and expander cone elements. Each of these elements is comprised of an outer slip portion 21 and a stagger spaced, inner expander cone portion 22, the portions being integrally cast and joined at their adjacent edges by connecting bridges or webs 23. The outer surface of slip portion 21 is provided with teeth or wickers 24 for grippingly engaging the well casing. The slip element may be provided with an exterior upper shoulder having a flat surface about which a spring steel retaining band 25 is positioned. Band 25, because of the inward spring force it supplies, provides a means for holding all the slip elements 21 together when bridges 23 are fractured upon setting of the slip, thus retaining them in a plane perpendicular to the axis of the well bore. While a retaining band has been shown, it will be appreciated that any equivalent stricture can be used to cause the alignments to move in unison.

A plurality of the combination slip and expander cone elements 21 and 2-2 are disposed about the well tool central mandrel 15 in a staggered, overlapping manner as shown in FIG. 2. One of the advantages of the present invention is that it may be utilized on various well tools of different diameters by merely using more or less of the one-piece castings, as required, to encircle the different sized mandrels of the various tools. The lower end surface of the expander cone portion of the one-piece casting may rest on the upper end of the packing element 18. The upper shoulder 27 of slip portion 21 engages the setting head 29. In this manner, when the setting tool is activated, a downward longitudinal force is applied to upper end surfaces 27 and an upward longitudinal force is applied to lower end surfaces of the castings 26. When this force exceeds the strength of connecting bridges 23, the bridges are sheared or fractured and the slip portion can move relative to the expander cone portion. As the connecting bridges 23 are positioned in the gaps 28 between overlapping, stagger spaced, slip and expander cone portions, the jagged edges left after fracturing do not come into contact with the surfaces bearing against each other during the expansion. Thus the inner surface of slip portion 21 engages the cooperatively shaped outer surface of the adjacent expander portion 22 without undue sliding friction. Continued application of longitudinal forces on surfaces 26 and 27 then forces the expander cone portions 22 longitudinally upward relative to slip portions 21, thus forcing the slip portions 21 to expand radially outward into engagement with well casing 11.

After the fracturing of connecting bridges 23 from each of the plurality of combination slip and expander cone segments distributed about mandrel 15, the spring steel retaining band 25 applies an inward radial force suflicient to clamp the separated members together and prevent them from sliding down the expander cone portions 22 and becoming unevenly engaged with the wall of casting 11. When full expansion has occurred, the oneway body lock 29 prevents downward motion of mandrel 15 relative to the setting head 30 and prevents disengagement of the upper and lower slips with the casing, thus locking the tool in position in the well bore. Details of one-way body lock 29 and setting tool 17 may also be found by reference to US. Patent 3,298,440.

The plurality of slip and expander cone segments of assembly 16 are preferably constructed of a material such as cast iron. This makes the tool readily removable from the well if desired at a later date. It will be appreciated that the segmented frangible construction of the present well tool anchoring system can readily be pulverized or drilled up by the action of a rotary drill bit. The plurality of arcuate segments of slip and expander cone are much more frangible than a conventional one-piece steel expander cone with a separate slip assembly.

Additionally, the one-piece casting of the present invention may be much more economically produced than slip and expander cone assemblies which require a large amount of machine tool work. Further, it is possible by appropriate sizing of the castings, to use one size of the combination slip and expander cone castings of the present invention on well tools of different diameters, thereby providing a much more versatile anchoring system than heretofore used in the art.

The anchoring system of the present invention has been described as the upper slip assembly and of course, it will be appreciated by those skilled in the art that the lower slip assembly can be formed in identical fashion with the elements oppositely disposed. Thus the lower slip assembly need not be further described.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes may be made without departing from this invention in its broader aspects and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. In a well tool for use in a well bore, an anchoring system comprising:

a plurality of arcuately shaped, one piece, frangible slip and expander segments, each adapted to be fractured along predetermined weakened sections into a slip portion and an expander portion, said slip portions cooperatively engageable with said expander portions to be expandable radially outward into engagement with the well casing.

2. The apparatus of claim 1 and further including means for retaining said slip portions in a plane perpendicular to the well bore during outward expansion.

3. As an article of manufacture, slip and expander means having an expander portion and a slip portion, said expander portion being a segment of a cone and having an inclined outer surface, said slip portion being a segment of a cone and having an inclined inner surface shaped complementarily to said outer surface of said expander portion, said slip portion having wickers formed on its outer periphery, said slip and expander portions being cast as an integral piece and joined together by a frangible portion adapted to be broken in response .to oppositely directed longitudinal force applied to said slip and expander portions, said slip portion being shiftable laterally of said expander portion by sliding engagement of said inclined surfaces after breakage of said frangible portion.

4. The article of manufacture of claim 3 wherein said frangible portion joins adjacent edges of said slip and expander portions.

5. Apparatus for use in anchoring a well tool in a well bore, comprising: a plurality of expander and slip segments coupled in side by side relationship about the well tool, said expander segments each having outer inclined surfaces, said slip segments each having inner inclined surfaces, said expander and slip segments being circumferentially staggered relative to each other in a manner whereby each slip segment overlaps an adjacent expander segment, and longitudinally disposed frangible means joining each slip segment to a respective expander segment so that the assemblage is formed by a plurality of integral pairs of slip and expander segments, longitudinal force applied in opposite directions to the ends of said slip and expander segments functioning to shear said frangible means and enable outward shifting of said slip segments by said expander segments.

6. The apparatus of claim 5 further including expansible means on said slip segments for causing said slip segments to be shifted outwardly in unison by said expander segments.

7. In a well tool for use in a well bore, the combination comprising:

a central mandrel;

expandable packer means for packing off the well bore;

slip and expander means carried on said mandrel for anchoring said tool in the well bore, said slip and expander means comprising:

a plurality of arcuately shaped, slip and expander pander portion, said slip and expander portion being cast of one frangible piece and joined at one adjacent edge by a plurality of breakable bridge pieces, the inner surface of said slip portion being shaped to cooperatively engage the outer surface of an adjacent one of said expander portions and the outer surface of said slip portion having a plurality of teeth for grippingly engaging the inner wall of the well casing, the inner surface of said expander portion being arcuately shaped to align with the outer surface of said central mandrel; and

means for applying oppositely directed longitudinal forces to said slip and expander segments to fracture said breakable bridge pieces and cause relative longitudinal motion of said slip and expander portions, thereby expanding said slip portions radially outwardly into gripping engagement with the well bore.

8. The combination of claim 7 and further including:

a radially inwardly biased expansible spring band about the upper portion of the outer surface of said plurality of slip portions for exerting an inwardly directed radial force to retain said slip and expander segments in a plane perpendicular to the Well bore during expansion.

References Cited UNITED STATES PATENTS 2,546,377 3/1951 Turechek 166-134 X 2,670,797 3/1954 Armentrout 166-136 2,901,046 8/1959 Webber 166-134 3,062,295 11/1962 Hanes 277-1162 3,298,440 1/1967 Current 166-134 X 3,393,742 7/1968 Bigelow et al. 166-134 X DAVID H. BROWN, Primary Examiner US. Cl. X.R.

segments each having two stagger spaced por- 40 166-123, 217

tions, a slip portion and a frusto-conical ex- 

